Abstract

Static and dynamic hysteresis loops of TbFeCo amorphousfilms are measured by vibrating sample magnetometry (VSM) and magneto-optical Kerr rotation. The static VSM loop shows a faster magnetization reversal than the static Kerr loop does. The dynamic Kerr hysteresis loop in a sinusoidal alternating magnetic field at shows a large increase in coercivity with respect to the static coercivity. The ultrafast dynamics of laser-induced demagnetization and magnetization recovery is studied by femtosecond time-resolved polar Kerr rotation spectroscopy, and shows a subpicosecond demagnetization and several hundreds of picosecond magnetization recovery process, which suggests gigahertz writing rate possible.

Received 27 April 2008Accepted 20 May 2008Published online 11 June 2008

Acknowledgments:

This work was supported partially by NSF of China under Grant Nos. 60678009 and 60490290, and by the doctoral specialized fund of MOE of China under Grant No. 20050558030, and by the National Basic Research Program of China (2007CB925104).